Netball: delaying play

Defending off court player.When a player in general play goes off court to improve her position , does the defender HAVE to allow her onto the court ? OR can she block her from returning. Eg shooter on one side of the circle goes off court around the goalpost and tries to return to court on the other side but defender {on court} blocks her from returning. Is this legal ???

My centre was penalised 3 times for not stepping into the centre circle directly at the centre pass. This seems a strange application of the deliberately delaying play rule, as she certainly was not doing it deliberately. What rule exactly was she infringing here?

I keep coming across situations of umpires reversing play for "pass not set". Typically where we want to take the pass speedily the ball is laid off, it is then being reversed as the offending player has not been standing by our side and ball given back to the offender. Surely this can not be the correct use of the rule? Some who contacts but then chooses not to set the penalty in time is then given the ball back? I understand it being reversed if the pass is not set from the correct position, but surely not for not waiting for the offender to be by our side!

My centre was penalised for stepping in the centre circle - she took her centre stance and after the whistle was blown she stepped out with one foot. I didnt think a centre had a 'landing foot' at a centre pass, providing both feet are in the circle when the whistle blows, but the umpire said when she returned to the circle she put her left foot in first so that became her landing foot even though play had not been started. I told her just to stay in the circle but I would like to know if the umpire was correct or if she had it wrong

Are you allowed to mark another player off court if you remain on court??

Need some help on a dispute on a decision I made during a match I was umpiring recently.A player was tying her shoe laces in my half of the court. A goal had been scored in the half I was umpiring. Centre stepped in the centre circle whilst this player was still attending to her shoe lace. So in affect she had not got herself on side and then gone off side she just did not get on side.I blew the whistle to start play as the centre was ready. As the player who was in my half and was off side, I blew for offside.Can I have clarification on this please, was I correct, or should the other umpire have called this offside even though the player was in my half?Secondly, a reputable umpire told me a couple of months ago, that the umpire blowing the whistle to start the game at a centre pass, controls both sides for off side? I.e. All players that go offside at the centre pass, to the left and right of the centre circle. I was not suite about this so need clarification on that too.Thanks in anticipation.

if a player goes off court can the defender prevent the player from coming back onto the court